We propose to investigate the isolation, structural elucidation and synthesis of certain biologically active substances including antitumor and carcinogenic sesquiterpenes, steroidal sex hormones and bacterial toxins which are lethal to disease carrying insects. The synthesis of a number of indanones related to the antitumor sesquiterpenes, illudin-S and -M, will be attempted. The indanones are present in bracken fern, Pteridium aquilinum, which is known to contain a potent carcinogen. The indanones will be submitted for tests for carcinogenic and antitumor activity. We would like to complete our investigation of steroidal hormones which are involved in sexual reproduction in the aquatic fungus, Achlya bisexualis. We have completed a practical synthesis of antheridiol, the hormone secreted by female strains of Achlya. Two new crystalline steroids have recently been isolated from achlya. These are secreted by male strains and induced the formation of oogonial initials, or female sex organs, in the female. The elucidation of the structures of the steroids is almost completed. A synthesis is planned starting from the readily available sapogenin, botogenin. Synthesis of 23-deoxyantheridiol, a steroid which we isolated from culture liquids of Achlya, will also be carried out. We have submitted and will continue to submit our synthetic steroids for reproductive physiology, cardiovascular, antitumor and other biological tests. Studies will be carried out on the isolation and identification of toxins produced by the bacterium, Bacillus sphaericus var. fusiformis, which are pathogenic to species of mosquito larvae and thus might be of potential value for controlling diseases transmitted by mosquitoes.